According to "The Merck Index", ninth edition, pages 815 and 816, Merck & Co., Inc., 1976, N-carboxy-3-morpholinosydnonimine ethyl ester (morsydomine) is a member of a class of non-benzene aromatic, heterocyclic and mesoionic type of compounds with stated pharmaceutical indications. Publications are cited therein with regard to developmental work stability studies and pharmacological studies on sydnone imines.